LOS ANGELES — A major electric provider in northern California began shutting off power to hundreds of thousands of customers to prevent power lines from sparking wildfires.
The Pacific Gas and Electric Company said that early Wednesday it began implementing the first phase of a "public safety power shutoff," expected to affect 513,000 customers in northern California, and that at noon (3 p.m. ET) a second phase affecting around 234,000 customers would begin.
Fire weather watches stretched the entire length of the state Tuesday as the National Weather Service said strong and damaging winds coupled with relatively low humidity created the "potential of rapid spread of fire."
Download the NBC News app for breaking news
"The time to prepare is now," the weather service said — a warning the state's power companies heeded.
PG&E said it would begin turning off power in stages to almost 800,000 residences and businesses in high-risk areas of 34 counties across the northern and central parts of the state. Outages could last days in some cases.
Evan Duffey, a senior meteorologist for PG&E, said Tuesday night: "By all metrics, this is forecast to be the strongest offshore wind event since October 2017."
An online outage map from the utility showed early Wednesday that power had been shut off in a large swath of northern California north and east of San Francisco up to the Redding area. The sheriff in Marin County, which is north of San Francisco, tweeted that the power was out there and urged people to treat dark traffic signals as four-way stops.
The second phase to begin at noon includes the San Francisco Bay area counties of Alameda, Contra Costa, Santa Clara and San Mateo, as well as father east, the utility said.PG&E said earlier that the blackouts were likely to affect parts of San Jose, Oakland and Berkeley but not San Francisco or Sacramento. A third phase is being considered that could affect another 42,000 customers, the utility said.
Meanwhile, Southern California Edison said it was considering shutting off electricity to more than 106,000 residential and business customers in parts of eight counties in the southern part of the state, including parts of Los Angeles, San Bernardino and Riverside counties. That utility said on Twitter late Tuesday that no power had been shut off.
"Turning off the power is an extremely difficult decision to make, because we know how much our friends, families and our communities rely on power," said Scott Strenfel, PG&E's principal meteorologist.
But Strenfel said the utility was expecting strong winds with gusts as high as 70 mph, which, coupled with low humidity, could lead to "catastrophic wildfire growth" in vulnerable areas of northern and central California.
Utilities count a single electricity account — residential or business — as a single customer, so the number of people who would be affected is well above 1 million. Because power will be turned off in stages depending on local timing of severe winds, PG&E said it couldn't pinpoint who would be shut off or for how long.
It said customers could have their power shut off even if they're not experiencing high winds, "because the electric system relies on power lines working together to provide electricity across cities, counties and regions."
And it urged northern and central Californians to stock up for the long haul. While hazardous conditions were expected to extend only into Thursday afternoon, crews can't go out to inspect damaged power lines and restore electricity until after the severe weather has passed, it said.
So "customers are being asked to prepare for an extended outage," PG&E said.
Ray Riordan, the emergency management director for San Jose, said Tuesday that in addition to the two days of high winds, it could take five more days for all areas to have their power restored.
"You can expect that we may not have power for seven days," he said.
Customers who lose business, relocate to cooler locations or have to throw out spoiled food won't be compensated, said Brandi Merlo, a spokeswoman for PG&E.
Because the shutdown is safety-related, "typically, in these cases, we do not reimburse customers for these losses," Merlo told NBC affiliate KRCA of Sacramento.
To make matters worse, PG&E's website — where the utility was directing customers to go to find out whether they were in one of the potentially affected areas — was balking Tuesday afternoon, failing to load pages related to the shutdown or returning broken links.
A spokesman for PG&E said Tuesday night that user volume up to eight times normal traffic was slowing the system. In response, PG&E posted individual power shutdown maps for all 34 affected counties on its Twitter account, @PGE4Me.
The utility has acknowledged that its equipment "probably" started the Camp Fire, which killed 85 people, destroyed thousands of structures last year and was the deadliest and most destructive fire in state history. It has previously declared so-called public safety power shutoffs when dry, windy conditions threatened to spark fires around power lines — this will be the fourth in the past month.
But the scale of this week's measures dwarf what's happened in the past. The utility shut down power to about 50,000 customers in northern California late last month and to about 24,000 customers the week before that.
"I don't think it's as disheartening as it is troubling," Nicki Jones, owner of Nic's Deli in Paradise, southeast of Redding, told NBC affiliate KNVN of Chico.
"The businesses here who do not have a backup generator — and they do lose food that they have to throw away — how many times would they be willing to do that?" Jones asked.
But Scott Anderson, who lives in Ben Lomond, in Santa Cruz County, said the shutoff was "a good thing."
"It's a good thing because if there was a fire in the valley here, it's going to be tough to avoid it," Anderson told NBC affiliate KSBW of Salinas.
"We have a backup generator on hand [and] have backup food, water in case something happens," he said.